I have a script to randomly change my wallpaper: /home/stew/bin/wallppr.sh. When I call the script, it works fine.

I'd like to call it every x time. I've tried the "watch" command, but I seem to need a dedicated terminal open at all times for that. After discovering crontab, it looks good (it can do hourly) so I've tried implementing it but it doesn't seem to have an effect.

When the cron job runs, it will likely have a minimalistic PATH so you probably have to specify the full path to your script in the crontab entry. I.e. /home/stew/bin/wallppr.sh and not just wallppr.sh. That may be the second rule of crontab: don't assume any PATH beyond /bin and /usr/bin.

Thanks for the link. I've now learned how to schedule my wallpaper script to run every 10 minutes, but it also fails now every 10 minutes.

The only information that I found here was that my system did not have /etc/cron.allow or /etc/cron.deny. I've therefore created /etc/cron.deny as an empty file to allow "all" users access to crontab. Unfortunately, this has had no effect when re-creating my crontabs.